US7706429B2 - BOC signal acquisition and tracking method and apparatus - Google Patents
BOC signal acquisition and tracking method and apparatus Download PDFInfo
- Publication number
- US7706429B2 US7706429B2 US11/533,142 US53314206A US7706429B2 US 7706429 B2 US7706429 B2 US 7706429B2 US 53314206 A US53314206 A US 53314206A US 7706429 B2 US7706429 B2 US 7706429B2
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- subcarrier
- boc
- subcarriers
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- code
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
- H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
- H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
- H04B2201/70715—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation with application-specific features
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0044—Control loops for carrier regulation
- H04L2027/0053—Closed loops
- H04L2027/0057—Closed loops quadrature phase
Definitions
- the present invention relates to processing of binary offset carrier (BOC) modulated signals (simply referred to as BOC signal hereinafter), more particularly, to a method and apparatus for processing BOC signals in acquisition and tracking modes of a satellite navigation receiver.
- BOC binary offset carrier
- GNSS Global Navigation Satellite System
- LBS location based service
- wireless multimedia communication and broadcasting signals is becoming an expectation.
- multi-specification LBS location based service
- a receiver able to support multi-mode receiving for GNSS signals can enhance locating precision and access to more services.
- different signal frequency bands support different services. As more and more bands need to be supported, band overlapping occurs.
- GPS is the U.S. navigation satellite system, which is a network of satellites continuously transmits high-frequency radio signals.
- the signals carry time and distance information that is receivable by a GPS receiver, so that a user can pinpoint the position thereof on the earth.
- Galileo the emerging European satellite navigation system, offers higher signal power and more robust modulation that will enable users to receive weak signals even in difficult environments. When combined, Galileo and GPS will offer twice the number of satellite sources as currently available. This provides redundancy as well as greater availability for the user.
- the combination of GPS and Galileo basically has four bands, excluding SAR (Safe and Rescue) service. GPS and Galileo systems share some signal bands. That is, GPS and Galileo share some central frequencies and send signals on the same ones of carriers.
- BOC Binary offset carrier modulation
- the BOC modulation is done by multiplying a pseudo-random noise (PRN) spreading coded signal (simply referred to as PRN coded signal hereinafter) with a square wave subcarrier (SC).
- PRN pseudo-random noise
- SC square wave subcarrier
- the SC has a frequency which is multiple of the code rate of the PRN spreading code.
- FIG. 1 is a waveform diagram showing the BOC modulation.
- the BOC-sine (simply referred to as BOC) signal is generated by mixing a SC-sine and a PRN coded signal, while the BOC-cos (also referred to as QBOC, where Q indicates “quadrature-phase”.) is generated by mixing an SC-cos and the PRN coded signal.
- the BOC signal has a symmetric split spectrum with two main lobes shifted from the center frequency by the frequency of the subcarrier.
- the characteristics of the BOC signal are dependent on the spreading code chip rate, the subcarrier frequency, and the subcarrier phasing within one PRN code chip.
- the common notation for a BOC-modulated signals in the GNSS field is represented as BOC(fc, fs), where f c is the code chip rate, and f s is the frequency of the subcarrier. Both fc and fs are usually represented as a multiple of the reference frequency 1.023 MHz. Therefore, the BOC signal can also be represented as BOC(n,m), where n is the multiple of 1.023 MHz for the PRN code chip rate fc, and m is the multiple of 1.023 MHz for the subcarrier fs.
- FIG. 1 is a diagram showing autocorrelation of BOC(1,1). That is, BOC(1,1) correlates with BOC(1,1). As shown, there are two troughs at both sides of the main peak in the middle. To calculate correlation power, square of correlation is usually used. Accordingly, the two troughs will cause two secondary peaks in view of correlation power.
- Such secondary peaks may cause a problem of mis-lock. That is, a receiver may lock the secondary peak rather than the main peak, and therefore resulting in erroneous tracking. A significant deviation of approximately 150 m would occur in the range measurement. Such an error is unacceptable in navigation.
- An objective of the present invention is to provide a BOC signal acquisition and tracking apparatus.
- the apparatus comprises a carrier unit generating a carrier; a code unit generating a BOC subcarrier, a QBOC subcarrier and harmonics of the BOC and QBOC subcarriers; and a code delay block receiving a signal, removing a carrier component from said signal by using said carrier from the carrier unit, respectively mixing the signal with the subcarriers output from the code unit, and integrating the mixing results; a combination unit combining the integration results to generate a combined correlation; and a discriminator generating a tracking error according to the combined correlation.
- the apparatus further has a controller.
- the controller controls the code unit to output which ones of the QBOC subcarrier and the harmonics of the BOC and QBOC subcarriers.
- the controller or the combination unit determines a coefficient for each integration result to be combined.
- the apparatus comprises a carrier unit generating a carrier; a code unit generating a BOC subcarrier, a QBOC subcarrier and harmonics of the BOC and QBOC subcarriers; a combination unit receiving the subcarriers and harmonics thereof, combining the same and outputting a synthesized subcarrier; a code delay block receiving a signal, removing a carrier component from said signal by using said carrier from the carrier unit, mixing the signal with the combined subcarrier, and integrating the mixing results; and a discriminator generating a tracking error according to the integration result.
- the apparatus further has a controller.
- the controller controls the code unit to output which ones of the QBOC subcarrier and the harmonics of the BOC and QBOC subcarriers.
- the controller of the combination unit determines a coefficient for each subcarrier to be combined.
- a further objective of the present invention is to provide a BOC signal acquisition and tracking method.
- the method comprises receiving a signal; generating a carrier; generating subcarriers including BOC subcarrier, QBOC subcarrier and harmonics thereof; removing a carrier component from said signal by using said carrier; mixing said signal with the subcarrier; and integrating the mixing result.
- the integration results for the respective subcarriers are combined to obtain a combined correlation.
- the subcarriers are combined as a synthesized subcarrier in advance. Then the received signal is mixed with the synthesized subcarrier and the integration of the mixing result is calculated.
- FIG. 1 is a waveform diagram showing generation of BOC and BOC-cos signals
- FIG. 2 shows correlation result of BOC (1,1) autocorrelation
- FIG. 3 is a block diagram showing a BOC signals acquisition and tracking apparatus in accordance with an embodiment of the present invention
- FIG. 4 is a block diagram showing a BOC signals acquisition and tracking apparatus in accordance with another embodiment of the present invention.
- FIG. 5 shows correlation powers of autocorrelation of BOC (1,1) and a combined correlation obtained in accordance with the present invention.
- FIG. 3 is a block diagram showing a BOC signals acquisition and tracking apparatus in accordance with an embodiment of the present invention.
- the apparatus can be implemented as a portion of a GNSS signal receiver (e.g. a Galileo receiver).
- the apparatus receives incoming IF data from an RF frond end of the GNSS receiver, for example.
- Reference number 10 indicates a carrier unit, which provides a carrier signal to carrier mixers 102 and 104 to remove IF component from the data.
- the carrier signal can be generated by a local oscillator, which is implemented by a carrier numeral controlled oscillator 12 .
- Reference number 14 indicates a phase shifter.
- the IF-removed signal in I and Q channels are then fed to mixers 202 and 204 , 206 and 208 , respectively.
- Block 20 is referred to as a code unit.
- the code unit 20 comprises a code numeral controlled oscillator 22 for providing an oscillation signal, a PRN code generator 24 receiving the code signal from the code NCO 22 to generate the PRN code, and a subcarrier generator 26 .
- the subcarrier 26 receives the PRN code to generate a BOC subcarrier, a quadrature-phase BOC (QBOC; also referred to as BOC-cos) subcarrier, a double frequency harmonic subcarrier of the BOC subcarrier, which can be represented as BOC-sin(2fs), and a double frequency harmonic subcarrier of the BOC-cos subcarrier, which can be represented as BOC-cos(2fs).
- QBOC quadrature-phase BOC
- the subcarriers are respectively fed to the mixers 202 - 208 , so that BOC modulated signals are generated.
- one subcarrier is fed to a pair of mixers for I and Q channels. Accordingly, for this case, at the code stage, eight mixers are needed since there are four subcarriers. For the sake of simplification and clarification, only four mixers 202 , 204 , 206 , 208 are shown in this drawing.
- the outputs of the mixers 202 , 204 , 206 , 208 which are referred to as code mixers, are fed into integration and dump units 302 , 304 , 306 , 308 , respectively, to be integrated and dumped. Then the integrated results from the integration and dump units 302 , 304 , 306 , 308 are fed to a combination unit 40 .
- the mixers 102 , 104 , mixers 202 - 208 and integration and dump units 302 - 308 compose a code delay block 30 .
- the combination unit 40 combines the integration results to obtain a combination correlation, which will be further described in detail.
- the combination result is then sent to a discriminator 50 .
- the discriminator calculates a tracking error.
- the apparatus of the present invention further comprises a controller 60 .
- the controller 60 receives the tracking error and outputs control signals to the carrier unit 10 and code unit 20 so as to adjust the carrier NCO 12 and code NCO 22 , respectively, according to the tracking error.
- the controller can also be designed to control the code unit to output which ones of the QBOC subcarrier and the harmonics of the BOC and QBOC subcarriers.
- FIG. 4 is a block diagram showing a BOC signals acquisition and tracking apparatus in accordance with another embodiment of the present invention.
- the structure shown in FIG. 4 is similar to that in FIG. 3 , the same reference numbers indicate the same components, and therefore the descriptions thereof are omitted herein to avoid redundancy.
- the apparatus of the present embodiment has a combination unit 41 rather than the combination unit 40 .
- the combination unit 41 receives subcarriers generated by the subcarrier generator 26 and synthesizes the subcarriers based on a built-in algorithm. That is, the BOC subcarrier, QBOC subcarrier and the harmonics thereof are combined in advance. Then the synthesized subcarrier is provided to code mixers 201 , 203 of I and Q channels.
- the outputs of the code mixers 201 , 203 are fed to integration and dump units 301 , 303 for respectively integrating the mixing results of I and Q channels.
- the outputs of the integration and dump units 301 , 303 are sent to the discriminator 50 to calculate the tracking error.
- the carrier mixers 102 , 104 , code mixers 201 , 203 , and integration and dump units 301 , 303 compose a code delay block 31 .
- the coefficients ⁇ , ⁇ , ⁇ are determined by the combination unit 41 in the present embodiment. However, those coefficient can also be determined by the controller 60 or externally given.
- the power curve obtained by this scheme is similar to that shown in FIG. 5 .
- the quadrature subcarrier thereof (QBOC), and double frequency harmonics of the BOC and QBOC subcarriers are utilized, other harmonics such as higher level harmonics of the BOC subcarrier and/or the QBOC subcarrier can be used.
- QBOC subcarrier and/or harmonic(s) thereof for example, that is, the coefficient(s) thereof is (are) set as zero. The flexibility of selection among those subcarriers is not limited.
Abstract
Description
R combi =R a +α×R b +β×R c +γ×R d (1)
where Ra=R2 BOC(1,1)/sin(fs), square of BOC(1,1) autocorrelation power
-
- Rb=R2 BOC(1,1)/cos(fs), square of BOC(1,1)/BOC-cos(fs) cross-correlation power
- Rc=R2 BOC(1,1)/sin(2fs), square of BOC(1,1)/BOC-sin(2fs) cross-correlation power
- Rd=R2 BOC(1,1)/cos(2fs), square of BOC(1,1)/BOC-cos(2fs) cross-correlation power
In this case, α=0.8, β=γ=1.FIG. 5 shows Ra, (i.e. the autocorrelation of the BOC(1,1) signal) and the Rcombi obtained by means of the above equation. As can be easily observed from this drawing, the secondary peaks of BOC autocorrelation function is significantly depressed. In the present embodiment, the coefficients α, β and γ are determined by thecombination unit 40. However, the coefficient can also be provided from another component such as thecontroller 60 or stored therein.
- Rb=R2 BOC(1,1)/cos(fs), square of BOC(1,1)/BOC-cos(fs) cross-correlation power
R combi =R 2 BOC(1,1)[sin(fs)+α cos(fs)+β sin(2fs)+γ cos(2fs) (2)
The coefficients α, β, γ are determined by the
Claims (20)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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US11/533,142 US7706429B2 (en) | 2006-09-19 | 2006-09-19 | BOC signal acquisition and tracking method and apparatus |
CN200710148236XA CN101150549B (en) | 2006-09-19 | 2007-08-28 | BOC signal acquisition and tracking method and apparatus |
TW096132543A TWI336177B (en) | 2006-09-19 | 2007-08-31 | Boc signal acquisition and tracking method and apparatus |
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US11/533,142 US7706429B2 (en) | 2006-09-19 | 2006-09-19 | BOC signal acquisition and tracking method and apparatus |
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US20080069187A1 US20080069187A1 (en) | 2008-03-20 |
US7706429B2 true US7706429B2 (en) | 2010-04-27 |
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US11/533,142 Active 2028-12-28 US7706429B2 (en) | 2006-09-19 | 2006-09-19 | BOC signal acquisition and tracking method and apparatus |
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CN (1) | CN101150549B (en) |
TW (1) | TWI336177B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100166045A1 (en) * | 2008-12-26 | 2010-07-01 | Altek Corporation | Method for obtaining precise sampling frequency of global positioning system (gps) |
US20140219393A1 (en) * | 2011-04-15 | 2014-08-07 | Huazhong University Of Science And Technology | Method for modulating navigation signal |
US9184973B2 (en) | 2014-01-10 | 2015-11-10 | Deere & Company | Method and receiver for receiving a binary offset carrier composite signal |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1933469B1 (en) * | 2006-12-12 | 2011-02-16 | STMicroelectronics Srl | Method and system for resolving the acquisition ambiguity and the problem of false lock in tracking BOC(n, n) modulated signals, particularly for satellite positioning/navigation systems |
US20080159198A1 (en) * | 2006-12-27 | 2008-07-03 | Mediatek Inc. | Boc signal acquisition and tracking method and apparatus |
US7991042B2 (en) | 2008-02-04 | 2011-08-02 | Mediatek Inc. | GNSS receiver and method for GNSS memory code generation |
EP2402787B1 (en) * | 2009-02-27 | 2019-01-09 | Furuno Electric Co., Ltd. | Gnss reception apparatus |
KR101381104B1 (en) * | 2013-05-22 | 2014-04-04 | 성균관대학교산학협력단 | Generating method for cboc correlation function, tracking method for cboc signal and tracking system for cboc signal |
EP3139199B1 (en) * | 2015-09-04 | 2018-12-26 | Airbus Defence and Space GmbH | Wireless communication unit, integrated circuit, satellite communication system and method for compensating for ionospheric group delay |
US9929887B1 (en) * | 2016-09-28 | 2018-03-27 | The Mitre Corporation | Backward-compatible signal variations for data augmentation |
EP3549377B1 (en) * | 2017-01-11 | 2022-04-20 | MediaTek Inc. | Efficient wide bandwidth operation and efficient ue-specific rf bandwidth adaptation |
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-
2006
- 2006-09-19 US US11/533,142 patent/US7706429B2/en active Active
-
2007
- 2007-08-28 CN CN200710148236XA patent/CN101150549B/en not_active Expired - Fee Related
- 2007-08-31 TW TW096132543A patent/TWI336177B/en not_active IP Right Cessation
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US20030231580A1 (en) | 2001-11-23 | 2003-12-18 | Nicolas Martin | Method and device to compute the discriminant function of signals modulated with one or more subcarriers |
US20060097915A1 (en) * | 2003-04-15 | 2006-05-11 | Thales | Method for the acquisition of a radio-navigation signal by satellite |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
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US20100166045A1 (en) * | 2008-12-26 | 2010-07-01 | Altek Corporation | Method for obtaining precise sampling frequency of global positioning system (gps) |
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US20140219393A1 (en) * | 2011-04-15 | 2014-08-07 | Huazhong University Of Science And Technology | Method for modulating navigation signal |
US9020072B2 (en) * | 2011-04-15 | 2015-04-28 | Huazhong University Of Science And Technology | Method for modulating navigation signal |
US9184973B2 (en) | 2014-01-10 | 2015-11-10 | Deere & Company | Method and receiver for receiving a binary offset carrier composite signal |
US9191061B2 (en) | 2014-01-10 | 2015-11-17 | Deere & Company | Method and receiver for receiving a composite signal |
US9197478B2 (en) | 2014-01-10 | 2015-11-24 | Deere & Company | Method and receiver for receiving a composite signal |
US9379765B2 (en) | 2014-01-10 | 2016-06-28 | Deere & Company | Method and receiver for receiving a binary offset carrier composite signal |
Also Published As
Publication number | Publication date |
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US20080069187A1 (en) | 2008-03-20 |
TWI336177B (en) | 2011-01-11 |
CN101150549B (en) | 2012-01-04 |
CN101150549A (en) | 2008-03-26 |
TW200815781A (en) | 2008-04-01 |
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